Club designers, including myself, have worked indefatigably over the last 20 years to improve golf ball distance travel by using various techniques to increase the spring effect of the clubhead facewall as it impacts the ball for a relatively few milliseconds. Contact between the clubface and ball occurs usually over only a distance of less than about 0.5 inches, even with driver type clubs.
Once considered illegal by the mercurial governing golf body, the United States Golf Association (USGA), such spring-like effect is now considered within the USGA Rules, as well as the Rules of the European R & A (Royal and Ancient) body.
Designers have approached these objectives in a variety of ways. One successful approach has been the thinning of the facewall around its perimeter so it flexes more where the facewall joins the crown wall, the toe wall, the heel wall and the sole wall. Another technique employed by Adams Golf, for example, is to form a slot in the sole wall just to the rear of the facewall and parallel thereto. Another similar technique is incorporated into the Taylormade Rocketbladez irons.
A third design, shown in the Blankenship, U.S. Pat. No. 7,288,030, assigned to Karsten Manufacturing Co., never adopted in any commercial club, shows two pistons attached to the rear surface that are dampened by a magnetic fluid in the piston chambers.
The problem in all these designs is that they do not satisfy the necessary face flexure criteria set forth in the abstract. That is, none of these designs frees the facewall to the maximum extent possible and hence have only limited face flexure.
It is a primary object of the present invention to ameliorate the above problems in the prior art.